1. Field of the Invention
The present invention relates to an optical part fixing chip, or more particularly, to an optical part fixing chip having a guide trench for fixing an optical part such as an optical fiber.
2. Description of the Related Art
An optical part fixing chip used to fix an optical part, such as an optical fiber needed for optical communication or the like has a guide trench generally. An optical part such as an optical fiber, an optical semiconductor device, or the like is fitted in the guide trench and thus locked therein. The optical part fixing chip is formed in, for example, a silicon substrate. Like another semiconductor device, after an optical part fixing substrate having a plurality of optical part fixing chips set in array is fabricated, the optical part fixing chips are cut apart using, for example, diamond blading, laser scribing, or diamond point scribing.
An optical semiconductor device using an optical part fixing chip is, for example, a semiconductor waveguide photo-detector.
An example of an optical part fixing chip used for such a semiconductor waveguide photo-detector is, as shown in FIG. 1, such that an optical fiber fixing trench 13 is bored in a silicon substrate 10 in order to position and fix an end of an optical fiber 11. Moreover, another example is, as shown in FIG. 2, such that a photodiode 12 is formed in the silicon substrate 10, a metallic electrode 16 is formed above the photodiode 12, and an optical fiber fixing trench used to position an optical fiber 11 relative to the photodiode 12 and fix it therein is bored.
Moreover, an example of an optical part fixing chip other than the one used for the semiconductor waveguide photo-detector has, as shown in FIG. 3, a guide ditch 3 is used to fix an optical part such as an optical fiber therein. The guide trench 3a is used to fix an optical semiconductor device such as a semiconductor laser therein.
Taking the chip shown in FIG. 3 for instance, a process of fabricating an optical part fixing substrate and then producing individual optical part fixing chips will be described briefly in conjunction with FIG. 4.
First, an optical fiber fixing trench 13 is bored within each optical part fixing chip in a silicon substrate or the like by performing anisotropic etching or the like. In consideration of the width of the blade of a cutter used at a subsequent dicing step, the optical fiber fixing ditches 13 are etched in the silicon substrate in such a way that cut sections of the optical fiber fixing trench 13 emerge on one end sections of chips after dicing step and one ends of the optical fiber fixing trench straddle over scribed lines 4 that serve as cutting lines employed at the dicing step. Thereafter, a cutter or the like is used to carry out cutting along the scribed lines 4, whereby individual optical part fixing chips are cut apart. This results in the optical part fixing chips like the one shown in FIG. 1.
However, the foregoing optical part fixing chip of a prior art has problems described below.
That is to say, according to the prior art, after an optical part fixing substrate is fabricated, when the substrate is diced, the blade of a cutter traverses, as mentioned above, the optical fiber fixing ditches 13 and guide ditches 3. Depending on the way of cutting, the finishing of the cut sections of the optical fiber fixing ditches 13 and guide ditches 3 may become unsatisfactory. More particularly, as shown in FIG. 3, a defect or dent may occur in a sectional part 20 of a trench. When the defect or dent occurs, when an optical part such as an optical fiber is mounted at a subsequent step, an optical part fixing chip may break. This becomes a factor of markedly deteriorating a manufacturing yield.